1. Field of the Invention
This invention relates to structure for providing support for circuit plug-in units, connectors and related wiring. Particularly, this invention relates to a structure for supporting prewired electrical connectors in aligned assembly with circuit boards.
2. Description of the Prior Art
A typical central office contains a plurality of bays of communications equipment including circuit modules which are interconnected, in some instances, with each other and with other facilities in the central office. Each bay includes a frame which extends from floor level nearly to the ceiling and supports a plurality of spaced, horizontally arranged shelves. Each shelf is integrally formed with a vertically oriented back portion. The back portion of each shelf support a plurality of connectors which are secured thereto. Each connector is provided with a plurality of terminal pins extending outwardly from the frame on one side of the connector. The opposite side of each connector is formed with a receptacle having contact elements for engaging printed wiring board terminations of the circuit modules. The contact elements are connected through the connector to the terminal pins on the other side thereof.
The circuit modules are positioned on the shelves with the terminations thereof inserted into the receptacles of associated connectors mounted on the back portions of the shelves.
As noted above, various ones of the circuit modules on any one bay are interconnected with each other and are also interconnected with circuit modules located in other bays and other facilities in the central office. In order to facilitate the interconnections required in the central office, wire wrap connections are made on the terminal pins extending from the connectors. Thus it is easily seen that a maze of wire wrap connections and associated wiring is required to provide the necessary interconnection between the various modules and other central office facilities.
Since each bay extends from floor level to essentially ceiling level, it would be most difficult to make wire wrap connections of terminal pins which are at or near floor level. In addition, it would also be difficult to make wire wrap connections at near-ceiling locations which would require a wire wrap operator to stand on a ladder or other platform. Further, in order to utilize as much of the central office floor space as possible, generally the space between rows of the bays is of limited access and would further hamper the movement of the wire wrap operator. Additionally, an extremely large number of wires is required within a central office in order to provide the necessary interconnections. Experience in wiring bays as described above has also shown that considerable time is also required to correct errors made in wiring made, on site, in the central office.
As one solution to the foregoing problems, each bay is assembled at an assembly shop wherein the connectors are secured to the back portions. The shelves and integrally formed back portions are then secured to a frame. The frame is then mounted on a stand so that the normally vertical axis of the frame is secured for rotation about a horizontal axis. This permits the positioning of the frame so that the terminal pins of all of the connectors extend in a direction which permits the wiring of various terminal pins on a point-to-point procedure by wire wrap operators.
A bank of terminal pins is also mounted on the frame at a central location to provide for interconnecting wiring between the bank and those terminal pins of the connectors of the bay which are to be ultimately connected to other bays and facilities in the central office. This provides an easily accessible location for wire wrap operations which must be performed at the central office. Thus, at the assembly shop, the wire wrap operators can also provide wiring from the terminal pins extending from each back portion to the bank of terminal pins at the central location on each bay.
The prewired bays are shipped to and installed in central offices. After the prewired bay has been installed in the central office, it is only necessary for a wire wrap operator to then make connections to the conveniently located bank of terminal pins at the central location of the bay in order to provide for interconnection between circuit modules of that bay to other bays and facilities in the central office. Circuit modules, which are shipped to the central office separately from the prewired bays, are thereafter inserted into the installed, prewired bays.
This procedure provides some solutions to the problems which would have been encountered if the bay had been wired entirely on location in the central office.
Each bay provides shelf support for various electrically different types of circuit modules. In some instances, the central office requirements do not call for a circuit module at every shelf position. Consequently, the bay is shipped to the central office for installation with some shelves being empty. However, in anticipation that future central office requirements will call for modules to be placed on some if not all of the empty shelves, and further, in order to avoid the previously mentioned problems of performing wire wrap operations in the central office when such modules are eventually called for, the entire bay is prewired as noted above in the assembly shop prior to shipping the partially module-filled bay to the central office. Thus, each bay that is shipped to a central office requires a full compliment of shelves and back portions with all terminal pins being interconnected to each other as required and to the bank of terminal pins of the central location even though not all shelves are contemplated for use at the time the bay is installed in the central office.
Therefore, a need exists to provide facilities and techniques for maintaining the advantages of prewiring the facilities at the assembly shop, but to eliminate the need for providing a fully wired compliment of shelves on each bay when not needed at the time the bay is shipped to the central office.